A typical damascene process for fabricating metal traces and via contacts in organic dielectric materials includes a number of steps. First, trenches and contact holes are formed in a dielectric material. Second, the trenches and contact holes are then metallized with a seed layer and subsequently filled with a metal using an electroplating process. To achieve complete filling of the trenches and contact holes, an overplating process is used (i.e., the metal is electroplated to a larger thickness than the desired thickness). Third, the electroplated metal is backetched to expose the traces and via contacts.
The typical electroplating process is designed such that more metal is deposited in the trenches than on the top surface of the dielectric material. The excessive metal deposited on top of the dielectric material is called an overburden. In the typical electroplating process, the overburden must be removed to expose the traces and via contacts.
The typical damascene process as described above has several disadvantages. One disadvantage of the typical damascene process is the slow deposition rate. The deposition rate is much slower than for the standard plating speed due to the plating and etching combination to avoid too large of an overburden on the top surface of the dielectric material. This results in a high process cost, especially when single wafer plating equipment is utilized.
Another disadvantage of the typical damascene process is the requirement for a very well-defined backetch process. For the backetch process, a very uniform overburden and a well-controlled backetch is mandatory. Such a well-defined backetch process is difficult to achieve.
For these and other reasons, there is a need for the present invention.